Conventionally, solder joint used to be widely employed for the electric connection for an electric device or an electronic device. In the conventional solder joint, Sn—Pb based eutectic solder is often used because the eutectic solder is suitable in view of practical use. However, it is urgently desired to develop a non-Pb based solder without Pb component because the Pb component contained in the Sn—Pb based eutectic solder is harmful to humans.
On the other hand, at present, as a jointing material to be used in a semiconductor device such as a semiconductor power device, a low temperature solder (Sn—Pb eutectic solder) with a melting point of 183 degrees centigrade and a high melting temperature type solder (Pb-5Sn based solder) with a melting point of about 300 degrees centigrade are often employed depending on the corresponding forming steps.
With the low temperature solder, an Sn—Ag—Cu based alloy solder comes into practical use and is promised as an alternative of the non-Pb based solder in many manufacturing companies for the years to come.
With the high melting temperature type solder, however, an Au-based alloy solder containing the Au component as a main component can be exemplified instead of the Pb highly contained solder. In view of the cost of the Au component which belongs to noble metal, it is difficult to generally employ the Au-based alloy solder. Then, although another metallic alloy solder containing another main component except the Pb component and the Au component is developed, the fungible metallic alloy solder does not come into practical use as the high temperature solder.
As of now, a Zn-based alloy jointing material is exemplified as a jointing material containing another main component except the Pb component and the Au components which can form the joint with a larger mechanical strength under high temperature of 260 degrees centigrade (refer to References No. 1 and No. 2). The Zn-based alloy jointing material is not expensive, and not harmful to the environment. However, since the Zn-based alloy jointing material can not exhibit the wettability for a Cu member, and is too hard to be employed as the jointing material, the Zn-based alloy jointing material does not comes into practical use.
Then, such an attempt is made as applying an Sn-based alloy jointing material as the high melting temperature type solder (refer to Reference No. 3). The Sn-based alloy jointing material can exhibit good jointing characteristics and hardness enough to be processed, but can not exhibit the thermal resistance enough to be applied as the high melting temperature type solder because the Sn-based alloy jointing material is liquefied at a lower temperature.    Patent Citation 1: Patent 2004-237357 (KOKAI)    Patent Citation 2: Patent 2001-121285 (KOKAI)    Patent Citation 3: Patent 2001-284792 (KOKAI)